I'd imagine you could transfer between battle net accounts, by contacting wow billing.

Multiple accounts on one B.Net account gets you:
- Much faster transfers between your own accounts, that are all on that B.Net account. You still pay the same price as before.
- The ability to switch from one account to another, within account management via a drop down menu.
- In the future, your friends list will be tied to your B.Net account, so you can chat with friends who are playing StarCraft II, while you're in WoW.
- You can set a new secret question for the B.Net account, even if you don't remember the secret question for the wow account.